The present invention relates to a method and apparatus for obtaining hydrogen, oxygen and ozone by efficient electrolysis of water.
Electrolysis of water is a technique that has been commonly practiced to produce hydrogen and oxygen (or ozone). In a typical system, hydrogen gas is produced in an electrolytic cell equipped with a diaphragm and containing an aqueous potassium hydroxide solution as an electrolyte. The product hydrogen gas is utilized, for example, as a hydrogen source in ammonia synthesis. A subject of interest that has drawn researchers' attention regarding the electrolysis of water involves methods of increasing the electric power utilization efficiency. An electrolysis process that has recently gained popularity employs a SPE (solid polymer electrolyte) cell wherein a fluorine resin based ion-exchange membrane used as a diaphragm is sandwiched between an anode and a cathode to form a solid electrolyte, as described in U.S. Pat. No. 4,416,747 and J. Elec. Chem. Soc., 132, p. 367 ff (1985). Electrolysis is performed with water supplied from the anode side that is transferred through the ion-exchange membrane toward the cathode side. Having various advantages including a minimum energy requirement for gas evolution, the SPE method is considered to be the most desirable of all techniques available for the electrolysis of water. However, in this method, the amount of water supplied at the anode which transfers toward the cathode is at least 4 to 5 times as much as the volume of water necessary for gas evolution at the cathode. Part of the transferred water must be taken out of the system, with a subsequent increase in the amount of water added and an increase in the operational complexity of system operation. If the transferred water accumulated in the cathode compartment is not removed from the system, the resulting pressure imbalance causes difficulty in recovering the gas evolved at the cathode. This problem has also been recognized in other methods of water electrolysis that employ conventional electrodes. The manner in which to deal with the excess catholyte has always been of great concern to those skilled in the art.